SAT OwlQuestion bank / Form, Structure, and Sense
In the 1950s, geologist Marie Tharp and her colleague Bruce Heezen analyzed thousands of depth measurements taken by ships crossing the Atlantic. Using these soundings to map the ocean floor, ______
Which choice completes the text so that it conforms to the conventions of Standard English?
the Mid-Atlantic Ridge was shown to contain a deep valley running along its center.
Tharp and Heezen showed that the Mid-Atlantic Ridge contained a deep valley running along its center.
a deep valley running along the center of the Mid-Atlantic Ridge was revealed.
the ocean floor's Mid-Atlantic Ridge turned out to contain a deep valley along its center.
Show answer and explanation
Answer: B
The introductory phrase "Using these soundings to map the ocean floor" describes the people who did the mapping. The subject that follows the comma must be those people. Only choice B places "Tharp and Heezen" immediately after the phrase; the other choices make a ridge or a valley the thing that used the soundings.
Choice A is a grammatical sentence on its own, but its subject, "the Mid-Atlantic Ridge," can't be the one using soundings to make a map.
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